Hydraulic torque transmission



Oct. 1, 19 40. HEPPNER 2,216,411

HYDRAULIC TORQUE TRANSMISSION Filed Nov. 13, 1937 s Sheets-Sheet 1 qo N ./NVENTOR MM 1) .5 mkm ATTORNEY Oct. 1, 1940. HEPPNER 2,216,411

HYDRAULIC TORQUE TRANSMISSION Filed Nov. 13, 1937 3 Sheets-Sheet 2 //V VE N TOR 72m 90711 ATTORNEY Oct. 1, 1940. HEPPNER 2,216,411

HYDRAULIC 'TORQUE TRANSMISSION Filed Nov. 13, 1937 3 Sheets-Sheet 3 "/NVENTOR ATTORNEY Patented Oct. 1, 1940 UNITE ],sTATEs nvnaauuc TORQUE TRANSMISSION Y Fritz Albert Max Hemmer, Golders Green,

' London, England Application'November 13, 1937, Serial No. 174,300 In Great Britain November 17, 1936 10 Claims.

This invention relates to hydraulic torque transmissions for use where it is desired to transmit torque from a source such as an engine to a variable load such as a road or rail vehicle.

5 It is of the kind incorporating a substantially toroidal space in which are located pump blades, turbine blades and reaction blades carried by respective wheels. I

A principal object of the invention is to pro- 10 vide a transmission which will automatically adapt itself to a wide range of torque ratios with high'efliciency whilebeing of simple construction. A further object is to provide a transmission which will automatically give an overdrive of high efliciencythat is to say will automatically give a higher secondary speed than primary speed when the secondary torque falls sufficiently below the primary torque. I

With these and other objects in view the invention resides in the combinations described below and defined in the claims.

A preferred embodiment of the invention, suitable'for use as in a motor road vehicle, is illustrated in the accompanyingdrawings together with certain modifications.

Figure lis a longitudinal section of the com plete transmission whichcan be used between th engine and the propeller shaft,

Figure 2 is a diagrammatic development of certain parts showing the profiles of the blades in the hydraulic circuit, I

Figure 3 is a detail partly in section showing a front view of the free wheel device,

Figure 4 is a. detail section on the line IV-IV Of Figure 1.

Figure 5 is a detail section showing a'modification in the structure of the pump wheel.

The example of hydraulic transmission illustrated comprises a primary or driving shaft I, 0 pump impeller wheel 2 thereon with blades 3, a driven or secondary shaft 6 carrying 8-. turbine wheel 5 with blades It, a first reaction wheel I! with blades l6,.and a second reaction wheel M with blades ll. The wheels together with a 5 core portion, in this example formed on wheels 2, ll, form a toroidalworking circuit for liquid.

The construction illustrated exemplifies a single stage hydraulic circuit, that late say there is only a single row of turbine blades In whichas trated the blades ll in the last row are fixed as one row as regards flow is more than counter- 10 I balanced by the extra complication and friction. v In the example the blades ii are on a wheel II and a free wheel device l5 between wheels 13 and H prevents backward rotation of' wheel I! with- 0ut-hindering forward rotation.

As will be seenin Figure 1, the blades I, It, I6, I! are arranged in that order in a toroidal space about the main axis of the transmission. Preferably, as shown the turbine blades III are set in the radially outermost part of the liquid 30 circuit. As shown in Figure 2 all the blades are of thickstreamline section with well rounded entry ends. The pump blades 3 are as shown steeply set that is to say approaching the or even substantially radial-and the outlet angle of the pump blades is greater than that of the turbine blades III. The. reaction blades II, II are-all substantially straight i. e. their streamline sections are symmetrical about a substantially straight axis. The first row, i. e. the row of blades it immediately succeeding the turbine blades ID are set substantially at 1. e. radially or axially and the last, fixed row II are set at a smaller angle than 90 the opposite way to the pump and turbine blades. The angle of the blades I1 is indicated at a Figure 2. Preferably. the fixed blades II are pitched at relatively large spacing and it will be observed that since the blades in each roware separately of complete-streamline section, any one row can be brought to rest by the reaction upon them in any angular position in relation to any other row without substantially aifecting the flow and therefore the efliciency of the circuit. This is an important-feature because it enables a wedge and roller type of free'wheel to be used which in turn enables the wheel I! to run forward freely when the conditions explained below arise. w a The circuit above described has the usual property of ability to increase the torque automati 1 cally on the secondary side in accordance with the loads and will do so emciently over the usual range uptoaratio of1to3or4. Atmaximum torque increase the liquid leaving the turbine blades has a rearward tangential component of velocity and accordingly it impinges backwards on the blades I but the latter cannot yield owing to the free wheel device II; the blades I! are also fixed and the liquid leaving blades l6 impinges on their sides l'lb. Thus the blades I 6, ll coact as stationary reaction blades which are essential if there is to be any change in torque between the primary and secondary shafts. As the blades II have well rounded inlet'ends they are able to receive and deal efficiently with liquid leaving the blades I 0 whatever its backward tangential component. As the blades i6 and I! are also of streamline section the latter are able to receive and deal emciently with the liquid leaving the blades II in whatever angular position about the axis of the Bear the free wheel device It brings the blades I! to and the liquid leaves the turbine blades with av forward component which, owing to the. free-.

wheel. causes the wheel IS with blades It to rotate forwards, the blades I. then acting as simple guide blades, but the blades I! still produce reactiorn When the 1:1 torque condition is reached the reaction torque completely 'disappears. blades ll substantially parallel to the blades l'l.

Under these conditions the blades I! as well as blades I I act as mere 'guide blades:

If now the secondary resistance falls the turbine wheel could not overrun the pump wheel without a stationary reaction member to provide consequent diflerence between primary and secondary torques; moreover this reaction torque must be in 'the opposite direction to that during torque increase and can only be provided by properly redirecting the liquid and not merely churning it. Such reaction is provided in the present invention by the blades II, the blades l8 continuing to rotate forwards. The blades II can furnish this required reaction torque firstly because the wheel l4 carrying .them being locked they do not yield to the liquid which now impinges on their sides I la, and secondly because as they are streamlined they can deal efliciently with this flow also, in other words theydo not causesubetantial energy losses but divert the liquid towards the centre and thus increase the vortex speed of-the liquid which being superposed on that imparted by the pump wheel increases the speed of theturbine wheel without the pump wheel running any faster, in other words the gear provides an overdrive. Owing to their rounded inlets the blades I! .can moreover deal efficiently with liquid reaching them over a fair angular range. By' thismeans an emciency. curve can be obtained. the more or less flat topped part of which extendsabove syn chronism of primary andsecondary speeds and the total emcient range of thegear is extended accordingly. The useful extra rangemay be up tit 25 per cent or more above primary speed;

The liquid now leaves the turbine The speed at which overdrive commences depends among other things on the angle of the fixed blades. For a small gear such as might tors such as induction motors, the angle may be adjustable. This may readily be arranged for by pivoting. the blades and providing each with a' toothed segment meshing with a toothed ring on a flared sleeve on the shaft of the wheel carrying the blades. The sleeve extends out of the circuit and is turned to adjust the blade angles as by a worm gear.

- Another feature of the present circuit is that the turbine if driven from the secondary side acts as an efficient pump and thus the engine of a vehicle can be started by the vehicle or act as a brake.

- To reduce blade friction, the blades as seen in side view in Figure 1 may instead of having straight leading edges, have concave leading edges. The concavity may be a continuous curve or it may be curved at the ends and straight in. the centre part. 'The blades. are still given the proper streamline section throughout 1. e. the concavity doesnot cut away the streamline leading end.

Referring still to Figure l more particularly it will be seen that the pump wheel 2 is rigid with a primary shaft l (driven directly or indirectly by the engine not shown) this shaft traversing the sleeve II. The parts I, 2 are borne by a bearing 4 in a rotating casing 5 which carries the turbine blades IO and is rigid with a secondary shaft 6 borne in the stationary casing 9 by a bearing 1, and a hollow final shaft I! by needle rollers I, the final shaft l8 itself I being borne in the casing 9 by bearings 8.

The hydraulic circuit is charged with any suitable liquid such as oil and during operation the liquid is kept 'under pressure by means of a centrifugal pump constituted by a plurality of suitable bores 20 in the pump wheel and passages '34 in the stationary wheel the latter passages 34 forming thestationary outlet blading of this centrifugalpump which discharges into the working circuit between the blades H. The passages 34 which actlike the diffuser of a centrifugal pump, are essential to develop sufficient pressure in the liquid to force it into the circuit. Since such a pump is relatively efiieient labyrinth seals which have considerable advantases can be used notwithstanding their relatively high leakage. Such seals are indicated at 2| between the pump wheel 2 and the stationary parts Ii, l4 at 22 between the reaction wheel ll and the rotating casing 5, and again at 23 between the casing! and the sleeve II. To catch liquid leaking past the labyrinth seals, rubbing seals are provided at 24 between the casing I and inside of casing I and at 25 between the shaft I and the outside of easing 9. Since the pressure of liquid escaping past the labyrinth seals is low the seals 24, 2! can be held up to their work by corrugated metal diaphragms 26, 2'!

respectively, which are cheap and simple in construction. Final leakage may be caught by means ofthrowers. I v

A reservoir of liquid into which leakage drains is provided by a sump 28 in casing 9. As shown in Figures 1 and 4 leakage checked by seal 24 reaches the sump through a passage 29, while as shown in Figure 4 other passages {I connect the sump 28 to the space 30a between shaft \l and sleeve 'H from which the pump constituted by bores 20 draws.

To enable any air or gases to escape from the centre of the circuit in the annular duct 3|, bores 32 are provided in the blades l'l. Other bores 33 in the wheel l3 enable most of the liquid escaping past the labyrinth 22 to return directly to the circuit. In consequence of this arrangement all gas will be carried off by the leakage past seal 23 and separated from the liquid in the sump 28. Openings may be cut through the 1 wheel I3 to relieve end thrust and give passage for the flow escaping from 3|.

It will be noted that by reason of the wheel arrangement no parts rotating in opposite directions are adjacent and that in fact adjacent parts of the several wheels are in successive order of speed so that liquid friction against the wheels themselves is at a minimum. Thus the adjacent surfaces of wheel 2 and easing 5 rotate relatively at only the speed difference of the primary and secondary shafts, while'the speed of wheel I3 is either substantially the same as that of casing 5, or of wheel l4 1-. e. zero. Further'it" will be seen that casing 5 rotates thus greatly facilitating cooling of the liquid in the circuit. If necessary the casing 5 can be finned. As above explained the wheel l3 may be brought to rest at any angular position in re lation to wheel l4 and a silent roller free wheel device I 5 is therefore used. As shown in Figure 3, this has the sloping tracks 35 formed in an external floating ring 36 while the rollers 31 run on a track 38 on the hub of wheel l3 and between projections 40 on the wheel l4. The ring 36 is biased towards engaged position by a spring 36a connected between it and the wheel l4. The use of a floating ring prevents jamming and enables the load to be at least partially equalized between the rollers notwithstanding unavoidable small inaccuracies in manufacture and assembly.

figure 1 shows the pump wheel 2 and blades 3' made in a single piece asby casting. It may instead be built up as shown in Figure 5. Here the blades have integral rivets 4|, 42 by which they are riveted between the wheel 2 and an inner core member-43. The bores 30 .are formed partly in the wheel 2, partly in the rivets 42 and blades 3, and partly in a ring 44 secured to the wheel by screws and retaining the bearing 4.

In the example illustrated in Figure 1 the drive is carried from the secondary shaft 6 to the final shaft I8 by a forward and reverse gear. The shafts 6 and 18 have splined portions in alignment at 45 and 46 respectively. Mounted on the splined portions is an internally splined axially slidable collar 41 which in the position shown in Figure 1 positively clutches the shafts 6 and I8 together; giving forward gear. The collar has formed integral therewith internally toothed orbit/ gear 48 and a plurality of pinions 49, one of which is seen in Figure l, mesh with the splines 45 which are of tooth form and the gear 48. The pinions are preventedfrom sliddirection at a reduced speed depending on the ratio of teeth 45 to teeth 43.

If desired an intermediate position may be provided in which teeth 54, 55 come into mesh before the collar leaves splines 45. In such position the whole gear is locked and changes from forward to reverse or vice versa must only be made when the secondary and tail-shafts are stationary. In-: stead there may be a neutral, free position between forward and reverse gears, in which case synchronising means of known kind, for example bevelled faces on the teeth coming into engagement are preferably provided, to hinder crashing of the gear. The sliding of the collar 41 may be effected in any convenient way, for example by a fork 56 and handle 51. I

What I claim is:

1. In a hydraulic torque transmission comprising a bladed pump wheel, a bladed turbine wheel and a bladed reaction member, forming asubstantially toroidal working circuit for liquid, the combination of a plurality of separate rows of reaction blades, said reaction blades all having a streamline section with well rounded inlet ends so that each row thereof may be at rest in'any angular position in relation to any other row, and means for preventing backward rotation of all of said reaction blades.

2. In a hydraulic torque transmission comprising a bladed pump wheel, a bladed turbine wheel and a bladed reaction member, forming a substantially toroidal working circuit for liquid, the combination of a plurality of separate rows of reaction blades, said reaction blades all having a streamline section with well rounded inlet ends, means for holding the last row of reaction blades stationary and means for preventing backward combination of two rows of reaction blades, said reaction blades all having a streamline section with well rounded inlet ends,the first row of reaction blades being set substantially in radial planes, means for preventing backward rotation of but permitting unrestricted forward rotation of said first row of reaction blades, and means for holding the second* row of reaction blades stationary.

4. In a hydraulic torque transmission comprisand a bladed reaction member, forming a substantially toroidal working circuit for liquid, the ing abladed pump wheel, a bladed turbine wheel combination of a plurality of rows of substantially straight reaction blades of streamline form with well rounded entry ends, the last row of reaction blades being set at an angle directing the fluid with a tangential component in the same direction of rotation as said pump wheel,

means for holding the last row of reaction blades 4 stationary, means for preventing rearward rotation of but permitting forward rotation of all reaction blades preceding said last row.

5. In a hydi'aulic transmission comprising a bladed pump wheel, a bladed turbine wheel ,and

acting with said runner, said runner and difluser coacting together to form a centrifugal pump drawing from said reservoir and discharging into said working circuit.

6."I n a hydraulic torque transmission comprising a bladed pump wheel, a bladed turbine wheel and a bladed reaction member, forming a substantially toroidal working circuit for fluid,

several rows of rotatable rows of reaction blades,

one fl'x'ed row of reaction blades succeeding said rotatable rows, the flrst row of reactionblades being set substantially in radial planes and successive rows being set at successively increasing forward angles, successively the fluid substantially toroidal working circuit for fluid,

the combination'of two rows only of reaction blades the flrst row being set substantially in radial planes and the last row set at an angle dilrecting'the fluid with a tangential component in the same direction of rotation as said-pump wheel, means preventing rearward rotation but permitting unrestricted forward rotation of said flrst row during normal running, and means holding said last row stationary. L

8. In a hydraulic torque transmission comprising a bladed pump wheel, a bladed turbine wheel and a bladed reaction member, forming a substantially toroidal working circuit for fluid, the combination of two rows of reaction blades one set at a substantially greater radius than the other, means preventingrearward but permitting unrestricted forward rotation of said greater radius row ofreaction blades, and means holding the other said row of reaction blades stationary.

9. In a hydraulic torque'transmission comprising a bladed pump wheel, a. bladed turbine wheel and a bladed reaction. member, forming a substantially toroidal working circuit for fluid, the combination of two successive rows of reaction blades the flrst row being at a greater radius than the second, means preventing rearward rotation but permitting unrestricted forward rotation of said flrst row during normal running, and means holding said second row of reaction blades stawheel and a bladed reaction member, forming a a substantially toroidal working circuit for. fluid, the combination of a row of axial flow turbine blades at the radially outermost part of said circuit, two successive rows of reaction blades following said turbine blades, the inlet of the flrst of'said rows of reaction blades being at approximately the same radius as said turbine blades,

the second of said rows of reaction blades lying radially within said flrst row, means preventing rearward rotation but permitting unrestricted forward rotatiom of said flrst row during normal running, and means holding said second row of reaction blades stationary.

FRITZ ALBERT MAX HEPPNER. 

